Ignition arrangement for a discharge tube

ABSTRACT

The invention relates to an arrangement for igniting a discharge tube provided with an external ignition electrode. According to the invention this discharge tube is ignited with the aid of a mechanically operable piezo-electric element. The invention leads to a simple ignition circuit. In addition, the use of the invention in the field of flashing equipment in photocameras has the advantage that exchangeability is possible so that different kinds of flash lamps can be flashed on one and the same camera.

United States Patent [191 Boekkooi et a].

[451 Jan. 1, 1974 1 IGNITION ARRANGEMENT FOR A DISCHARGE TUBE [75]Inventors: Anton Boekkooi; Meerten Luursema; Taeke Tol, all ofEmmasingel, Eindhoven,

Netherlands [73] Assignee: U.S. Philips Corporation, New

York, NY.

[22] Filed: Dec. 3, 1971 [21] App]. No.: 204,461

[52] 11.8. CI 95/ll.5 R

[51] Int. Cl. G03b 15/03 [58] Field of Search 95/11.5. R, 11 L; 315/55,241 P [56] References Cited UNITED STATES PATENTS 2,538,577 1/1951McCarty 95/11 3,581,637

6/1971 Harvey 95/11 2,856,564 10/1958 Derwin 315/241 UX 2,972,937 2/1961Suits 3,21 1,069 10/1965 Rigiton 3,528,354 9/1970 Nakagawa 95/11.5

Primary Examiner-Samuel S. Matthews Assistant Examiner-Michael L.Gellner Attorney-Frank R. Trifari [5 7 ABSTRACT The invention relates toan arrangement for igniting a discharge tube provided with an externalignition electrode.

According to the invention this discharge tube is ignited with the aidof a mechanically operable piezo-electric element. The invention leadsto a simple ignition circuit. In addition, the use of the invention inthe field of flashing equipment in photocameras has the advantage thatexchangeability is possible so that different kinds of flash lamps canbe flashed on one and the same camera.

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sum u or 4 nus ANTON BOEKKOOI MEERTEN LUURSEMA TAEKE TOL AGENT IGNITIONARRANGEMENT FOR A DISCHARGE TUBE The invention relates to an arrangementfor initiating an electric discharge in a gas and/or vapour dischargetube which is provided with two main electrodes and an externalauxiliary electrode.

An arrangement of the kind described above is shown, for example, inFIG. 2 of the magazine article Recent developments in electronic flashlamps, Philips Technical Review, Volume 22, 1960/1961, no 12, pages377-390. A drawback of this known arrangement is that it is not suitableto ignite the discharge tube starting from an impact pressure. A furtherdrawback of this known arrangement is that its ignition circuit isfairly complicated, for a capacitor and a transformer are required. Afurther drawback of the known arrangement is that it cannot be usedwithout further steps in a photocamera which is provided with anarrangement including a piezo-electric element and a mechanicaloperating member for this element.

An object of the present invention is to provide an arrangement of thekind described in the preamble which on the one hand leads to anignition of a discharge tube by means of an impact pressure, and on theother hand makes it possible to use also a discharge lamp as a flashlight source in combination with a photocamera and a piezo-electricelement and an operating member therefor.

According to the invention, an arrangement for initiating an electricdischarge in a gas and/or a vapour discharge tube which is provided withtwo main electrodes and an external ignition electrode, is characterizedin that the arrangement includes a mechanically operable piezo-electricelement which supplies an electric voltage to the ignition electrode forinitiating the discharge in the tube.

An advantage of an arrangement as described above is that it can bringabout an ignition of the discharge tube also by means of an impactpressure.

The signal which is generated by the piezo-electric element may bepassed, for example, through a transformer to the ignition electrode ofthe discharge tube.

ln an advantageous embodiment of an arrangement according to theinvention in which the piezo-electric element is provided with twooutput terminals, one output terminal of the element is connectedthrough a substantially impedance-free connection to the ignitionelectrode of the discharge tube, and the other output terminal isconnected through a likewise substantially impedance-free electricalconnection to a main-elec-- trode of the tube.

An advantage of this preferred embodiment is that the ignition circuitfor the discharge tube may be very simple.

The discharge tube may be a discharge lamp, but this is not necessary.It may alternatively be a quench tube which in principle need notradiate light, but has a switching function only.

In a further special embodiment of an arrangement according to theinvention suitable for use in combination with a photocamera which isprovided with a member for the mechanical operation of thepiezo-electric element, the discharge tube is a gasdischarge flash tube.

An advantage thereof is that this leads to a very simple combination ofa photocamera and an electronic (gas discharge) flash unit.

It is possible that the previously mentioned combination of photocameraand gas discharge flash tube constitutes a unit in which flash lamps ofa different type cannot be used.

In a further advantageous embodiment of the arrangement, which inaddition to initiating a discharge in a gas discharge flash tube is alsosuitable for the ignition of a high-voltage combustion flash lamp, thereare at least two lamp holders both of which are electrically connectedto the piezo-electric element and in which one lamp holder is suitablefor a gas discharge flash lamp and the other lamp holder is suitable fora highvoltage combustion flash lamp.

An advantage of this arrangement is that flashing can take place bothwith a gas discharge flash lamp and with a high-voltage combustion flashlamp by means of the same camera and the same piezo-electric element.Consequently, this unit is fairly universal.

In a further special arrangement which is likewise suitable for flashingwith the aid of a gas discharge flash lamp and a high-voltage combustionflash lamp, one holder for a lamp is provided which is electricallyconnected to thevpiezo-electric element and which holder is suitable forboth a gas discharge flash lamp and for a high-voltage combustion flashlamp.

An advantage of the last-mentioned embodiment is that only one holder issufficient.

It is possible to accommodate the electronic flash lamp and thepiezo-electric element in different detachable parts of the arrangement.

In a further special arrangement according to the invention theelectronic flash lamp and the piezo-electric element form part of oneand the same structural unit.

An advantage of this preferred embodiment is that a compact unit isobtained.

In another special embodiment of an arrangement according to theinvention, the piezo-electric element is accommodated in an adaptorwhich in the operating condition of the arrangement is present betweenthe photocamera and a unit comprising the electronic flash lamp. j

An advantage of this embodiment is that, when the camera is providedwith an operating member for the piezo-electric element, three types offlash lamps can be flashed with the camera. The first possibility is toignite the electronic flash lamp with the aid of the adaptor and thepart comprising the electronic flash lamp,

the second possibility is to place a high-voltage combustion flash lampon the adaptor instead of the unit which comprises the electronic flashlamp, and the third possibility is to remove the adaptor from the cameraand to use the operating member projecting from the camera to ignite aso-called percussion flash lamp. The embodiment mentioned above thus isquite universal.

As already described hereinbefore, the invention may be used in thefield of generating light flashes for taking photographs. However, it ispossible to extend the scope of the present invention to other fields,namely to fields using discharge lamps for general i1- luminationpurposes, which thus do.not have a flashing character.

Thus, in-a further special embodiment of an arrangement according to theinvention, the discharge tube is a discharge tube for generalillumination purposes, in which the ignition voltage of the lamp is 300Volts at a minimum and the voltage of the supply source for supplyingthe lamp current is lower than the ignition voltage of the lamp, and apiezo-electric element is present such that when it is mechanicallyoperated a voltage is set up at the ignition electrode of the lamp,which voltage is sufficient to produce a breakdown between the mainelectrodes in case of a voltage between the main electrodes of the lampwhich is equal to that of the supply source for supplying the lampcurrent.

An advantage of the last-mentioned arrangement is that discharge lampsfed by normal supply mains lines can also be ignited in a simple mannerat a relatively high ignition voltage, namely without using auxiliaryarrangements such as electronic starters, etc.

In the case of discharge lamps which are not provided with an outerenvelope, for example, low-pressure mercury vapor discharge lamps, oneof the output terminals of the piezo-electric element might beelectrically connected to an ignition strip on the outer side of thelamp. In other cases there will be lamps which are provided with anouter envelope. Thus, for example, in a special arangement according tothe invention the lamp is a high-pressure sodium vapour discharge lampprovided with an outer envelope and equipped with a third electriclead-through which is connected to an external auxiliary electrode ofthe discharge tube. In this case the piezo-electric element is providedoutside the lamp and is connected between the third and one of the otherelectric Iead-throughs of the lamp.

It is known that high-pressure sodium vapour discharge lamps have arelatively high lumen value, but on the other hand the ignition voltageis relatively high. According to the present invention such a lamp maybe ignited in a very simple manner with the aid of a piezoelectricelement.

In a further arrangement according to the invention the piezo-electricelement is accommodated in an auxiliary circuit in which the operatingmember of this piezo-electric element can be operated manually, forexample, by means of a push-button which hits the piezo-electricelement. This auxiliary circuit may be provided, for example, close to alamp to be ignited, for example, a high-pressure sodium vapour dischargelamp. This may be effected, for example, on the outer side of thefitting which accommodates this lamp.

A special embodiment of the last-mentioned preferred embodiment isformed in such a manner that the operating member of the piezo-electricelement is coupled to a switch for switching on the lamp.

This special embodiment has the advantage that when the switch isswitched an impact is produced on the piezo-electric element so that thelamp receives an ignition pulse.

In order that the invention may be readily carried into effect, someembodiments thereof will now be described in detail, by way of example,with reference to the accompanying diagrammatic drawings, in which:

FIG. 1 shows a circuit diagram of an arrangement according to theinvention,

FIG. 2 shows a further circuit diagram of an arrangement according tothe invention,

FIG. 3 shows an arrangement according to the invention provided with anelectronic flash lamp,

FIG. 4 shows a further arrangement according to the invention which isprovided with both an electronic flash lamp and a high-voltagecombustion flash lamp;

FIG. 5 shows a further arrangement according to the invention in which apiezo-electric element is provided in a photocamera, and

FIG. 6 shows an arrangement according to the invention provided with ahigh-pressure sodium vapour discharge lamp.

In FIG. I, the reference numeral 1 denotes an electronic (gas discharge)flash lamp. The reference numeral 2 denotes a piezo-electric element. Anelectric supply wire of element 2 is connected through a resistor 3 anda Zener diode 4 to a further output terminal 5 of the piezo-electricelement 2. The connection between resistor 3 and Zener diode 4 isconnected to the ignition electrode of a thyristor 6. The anode of thethyristor is connected to a primary winding 7 of a transformer. Thecathode of thyristor 6 is connected to a point located between Zenerdiode 4 and connection terminal 5 of the piezo-electric element. Theother side of the primary winding 7 of the transformer is connected to apoint 8 located between two resistors 9 and 9'. Resistors 9 and 9constitute a bridge across the discharge lamp 1. Resistor 9 isfurthermore shunted by a capacitor 10. The secondary winding 11 of thetransformer, whose primary winding is denoted by the reference numeral7, is connected at one end to the cathode of thyristor 6 and at theother end to an external ignition electrode 12 of discharge lamp 1. Thereference numeral 13 denotes a direct current source. The positiveterminal of this source is connected through a switch 14 to a maincapacitor 15. The other electrode of capacitor 15 is connected to thenegative terminal of the voltage source 13. The lamp 1 is connectedacross capacitor 15.

The arrangement of FIG. 1 operates as follows. First the switch 14 isswitched on so that capacitor 15 is charged by voltage source 13. Inorder to ignite the discharge lamp a blow or impact may be exerted onthe piezo-electric element 2. In fact, when this impact is produced, anelectric voltage is generated in element 2. This voltage will produce avoltage across Zener diode 4 which voltage is higher than the ignitionvoltage of thyristor 6. When thyristor 6 conducts, a current will flowfrom capacitor 10 via primary winding 7 and thyristor 6. In fact,capacitor 10 has previously been charged via resistor 9 when the switch14 was switched on. The current flowing through primary winding 7 of thetransformer incudes a voltage in the secondary winding 11, which voltageis sufficiently high to ignite the discharge lamp 1 through the triggerelectrode 12. When, for example, switch 14 is open before flashing, theflash lamp 1 will be extinguished after ignition, namely after a givendischarge of capacitor 15.

In one embodiment the electronic flash lamp 1 was a lamp having anelectrode distance of approximately 37 mms and a filler gas consistingof xenon at a pressure of approximately 340 Torr. The supply source 13had a voltage of approximately 350 Volts. The capacitance of capacitor15 was approximately 500 ,uFarad and the capacitance of capacitor 10 wasapproximately 0.1 ,uFarad. The resistor 9' had a value of approximately750 k.Ohms and the resistor 9 had a value of approximately I M.Ohm. Uponclosing switch 14, capacitor 10 was consequently charged toapproximately 200 Volts. The resistor 3 had a value of approximately 82k.Ohms. With mechanical operation, the piezo-electric element 1 couldgenerate an electric voltage of approximately 500 Volts for severalmicroseconds in the circuit arrangement of FIG. 1. This was sufficientto drive thyristor 6 into conduction through its control electrode.Subsequently capacitor, 10 was discharged through the primary winding 7of the transformer. The voltage induced thereby in the winding 11produced a voltage pulse on the auxiliary electrode 12, which pulsecaused the lamp 1 to ignite.

The circuit of FIG. 1 may be used, for example, if the distance betweenthe piezo-electric element and the lamp 1 is relatively large.

FIG. 2 shows in principle the same circuit arrangement as that ofFIG. 1. The circuit for igniting the lamp, which is denoted by thereference numeral in FIG. 2 is, however, much simpler. This may beexplained as follows. The reference numeral 21 denotes a piezoelectricelement. This element is connected directly (through a substantiallyimpedance-free connection) to an external ignition electrode 22 of anelectronic flash lamp 20. The other end of the piezo-electric element isconnected to a main electrode 23 of the lamp 20. The reference numeral24 again denotes a direct voltage source, which is connected through aswitch 25 to a main capacitor 26. The lamp 20 is switched acrosscapacitor 26.

The operation of the circuit of FIG. 2 is as follows. First the switch25 is closed so that main capacitor 26 is charged. However, the lampdoes not ignite yet. When a mechanical impact is exerted on thepiezoelectric element 21, a high electric voltage will be producedbetween trigger electrode 22 and main electrode 23 in such a manner thatthe lamp 20 is ignited. If switch 25 is opened prior to flashing, thelamp 20 is extinguished after an ignition and after a given discharge ofcapacitor 26. It is of course feasible that the lamp 20 may beextinguished in a different manner. The discharge tube 20 may beextinguished, for example, by means of a so-called quench tube (notshown) connected across the discharge tube and commanded, for example,through a photosensitive element. This photosensitive element mayreceive light reflected by an object to be photographed, whereby thisobject is radiated by the flash lamp 20.

In the arrangement of FIG. 2 the piezo-electric element 21 in oneembodiment was of the same type as the element 2 of FIG. 1. This element21 produced a voltage of approximately 3 k Volt upon mechanicaloperation (in its electrically unloaded state as is shown in FIG. 2).The lamp 20 was then ignited. In the circuit of FIG. 2, it is to benoted in connection with the ignition that the distance between thepiezo-electric element and the lamp is not too large.

In FIG. 3, the reference numeral 30 denotes a photocamera. Thisphotocamera has a lens which is denoted by the reference numeral 31. Aconnection block having two swallow-tail recesses is provided on top ofthe camera. This block is denoted by the reference numeral 32. A pin 33partly protrudes from the block 32. The pin 33 is coupled in a mannernot further shown to a shutter mechanism of the lens 31. The operationof the shutter mechanism results in the pin 33 being flipped upwards.The reference numeral 34 denotes as electronic structural flash unitwhich is provided with a gas discharge flash lamp 35. The base of theunit 34 includes a piezo-electric element 36. Electrical connectionwires (37,38) are connected between this element and a main electrodeand an auxiliary electrode 39 of the lamp 35. The other supply equipmentof the lamp 35 such as, for example, a main capacitor which is denotedby the reference numeral 26 in FIG. 2, is not further shown in FIG. 3.However, the electrical circuit may be formed in a similar manner as inFIG. 2. When pin 33 is flipped upwards, the piezo-electric element 36 isstruck and thereby generates a voltage which is set up at the auxiliaryelectrode of the lamp 35. This combination of camera and flash unit 34is suitable for taking flash photographs.

In FIG. 4 the reference numeral 40 denotes a photocamera whose lens isdenoted by the reference numeral 41. The reference numeral 42 denotes apin which partly protrudes from the camera. This pin is coupled to theshutter mechanism of the lens 41. The reference numeral 43 denotes anadapter which is provided with a piezo-electric element 44. Furthermoretwo structural units are shown, namely unit 45 comprising a gasdischarge flash lamp 46 and unit 46 comprising a highvoltage combustionflash lamp 48. Electrical connections (49", 49", and 50", 50) are passedfrom the piezoelectric element 44 to the lamp 46 in the structural unit45, as well as connections (51, 52) which are passed to the lamp (48) inthe structural unit 47. A change-over switch (not shown) is provided sothat a current can flow either to lamp 46 or to lamp 48. When the lensof this camera is opened, the pin 42 strikes the crystal 44 and,dependent on the position of said switch, either the discharge lamp 46or the high-voltage combustion flash lamp 48 is ignited. It is of coursefeasible that the structural unit 47 is not only provided with onecombustion flash lamp 48, but with a magazine of combustion flash lampswhich in an electrically parallel arrangement are juxtaposed on theupper side of the camera.

In FIG. 5, the referencenumeral denotes a photocamera having a lenswhich is denoted by the reference numeral 61. This camera includes anoperating member for a piezo-electric element and the piezo-electricelement itself. The latter is denoted by the reference numeral 62. Ablock having swallow-tail recesses is provided on top of the camera.These recesses are shown in a cross-section and are denoted by thereference numerals 63 and 64, respectively. A structural unit 65, whichis provided with an electronic flash lamp 66, is slid around blocks 63and 64. The reference numerals 67 and 68 denote electrical connectionsbetween the piezo-electric element 62 and the parts 63 and 64,respectively, and subsequently to the electronic flash lamp 66. Thus,this unit is suitable for taking flash photographs with the aid of a gasdischarge flash lamp. The unit may, optionally be replaced by the unit(47, 48) of FIG. 4.

FIG. 6 shows a high-pressure sodium vapour discharge lamp and a fittingtherefor, and an electric sup ply circuit. In this Figure the referencenumeral 81 denotes a glass outer envelope of the lamp. In this case alamp is provided of approximately 400 Watts having a length ofapproximately 27% cm. The reference numeral 82 denotes a lamp base ofthebayonet type. The reference numeral 83 denotes a discharge tube inthe outer envelope 81. A part of the discharge tube 83, namelypart 83a,is shown in a longitudinal section. The reference numeral 84 denotes astem through which three electric supply conductors 85, 86 and 86 arepassed. Conductor is electrically connected to a conductor 87 which isinserted at the other end into a tubular current supply member 88provided at one end of the discharge tube 83. A stranded wire 89 issecured to the conductor 87, which wire is in electrical contact withthe outer circumference of the current supply member 88. The supplyconductor 86 is connected to a terminal wire which consists of astraight part 90 and a part 91 provided with a convolution 92 passedaround an indent in one end part of the outer envelope 81. A rigidcurrent supply strip 93 which is electrically connected to a tubularcurrent supply member 94 of the discharge tube 83 is secured to one endof the straight piece of the terminal wire 90. The reference numeral 95denotess an external auxiliary electrode in the form of a convolution oftungsten wire having a thickness of approximately 0.24 mm. Thisauxiliary electrode is electrically connected to conductor 86. Theauxiliary electrode is provided around the discharge tube. The averagedistance between the auxiliary electrode and the discharge tube is aquarter of a millimetre. The reference numerals 96 and 97 denote themain electrodes of the discharge tube 83.

In one embodiment the diameter of the outer envelope 81 wasapproximately 4.6 cms and the external diameter of the discharge tube 83(83) was approximately 0.95 cm. The length of the discharge tube 83 wasapproximately 11.5 cms and the distance between the main electrodes 96and 97 was approximately 8 cms. The distance between the auxiliaryelectrode 95 and the main electrode 96 was approximately 23 mms. Thedischarge tube 83 contained an ignition gas, namely xenon in addition tosodium and mercury.

The lamp described was connected in series with an inductance 98 ofapproximately 0.12 Henry and in series with a diagrammatically shownrotatable switch 100 to an alternating voltage supply of 220 Volts, 50Hz. To this end, the lamp base 82 was first inserted in the fitting 99.

Upon closing the series arrangement by rotating the switch 100, the part101 of switch 100 ensured closing of the main circuit. However, when theswitch was rotated, the part 102 of switch 100 struck a piezo-electricelement 103 incorporated in switch 100. This impact was converted intoan electric voltage pulse, which was applied to the ignition electrode95 through the conductors 104 and 86". The lamp was then ignited. If thelamp does not ignite for the first time, the switch 100 has to berotated a number of times until one of these further starting attemptsresults in the ignition of the lamp.

We claim:

1. A light flashing device in combination with a photocamera comprising,a gas discharge flash lamp having two main electrodes and an externalignition electrode, a mechanically operable piezoelectric element havinga pair of output'terminals for supplying an electric ignition voltage tosaid ignition electrode, said photocamera comprising at least two lampholders and a member for mechanically operating the piezoelectricelement and coupledthereto, one lamp holder being adapted to hold a gasdischarge lamp and the other lamp holder being adapted to hold ahigh-voltage combustion lamp, and means electrically connecting theterminals of each lamp holder to the output terminals of thepiezoelectric element so that one output terminal of the piezoelectricelement is connected to the ignition electrode of the discharge lampthrough a substantially impedance-free connection and the other outputterminal of the piezoelectric element is connected to a main electrodeof the lamp through a second substantially impedance-free electricconnection.

2. A light flashing device in combination with a photocamera comprising,a gas discharge flash lamp having two main electrodes and an externalignition electrode, a mechanically operable piezoelectric element havinga pair of output terminals for supplying an electric ignition voltage tosaid ignition electrode, said photocamera comprising a member formechanically operating the piezoelectric element and coupled thereto anda lamp holder adapted to hold both a gas discharge lamp and ahigh-voltage combustion lamp, means connecting one output terminal ofthe piezoelectric element to the ignition electrode of the dis chargelamp through a substantially impedance-free connection that includes aterminal of the lamp holder, and means connecting the other outputterminal of the piezoelectric element to a main electrode of the lampthrough a second substantially impedance-free electric connection thatincludes a second terminal of the lamp holder.

3. A light flashing device in combination with a photocamera comprising,a gas discharge flash lamp having two main electrodes and an externalignition electrode, a mechanically operable piezoelectric element havinga pair of output terminals for supplying anelectric ignition voltage tosaid ignition electrode, said photocamera comprising a member formechanically operating the piezoelectric element and coupled thereto andan adapter for mounting and electrically coupling a gas discharge lampand a high-voltage combustion lamp to the terminals of the piezoelectricelement, said piezoelectric element being mounted in said adapter, meansconnecting one output terminal of the piezoelectric element to theignition electrode of the discharge lamp through a substantiallyimpedance-free connection, and means connecting the other outputterminal of the piezoelectric element to a main electrode of the lampthrough a second substantially impedance-free electric connection.

4. A light flashing device comprising, an electric discharge tube havingtwo main electrodes and an external ignition electrode, a mechanicallyoperable piezoelectric element having a pair of output terminals forsupplying an electric ignition voltage to said ignition electrode, apair of supply terminals connected to the main electrodes of the tubeand adapted to be connected to a source of voltage that is lower thanthe tube ignition voltage, means connecting one output terminal of thepiezoelectric element to the ignition electrode of the discharge tubethrough a substantially impedancefree connection, and means connectingthe other output terminal of the piezoelectric element to a mainelectrode of the tube through a second substantially impedance-freeelectric connection, said piezoelectric element including an auxiliarycircuit with which the operating member for the piezoelectric elementcan be operated manually, said auxiliary circuit further comprising aswitch for switching current to the main electrodes of the tube, andmeans mechanically coupling the operating member for the piezoelectricelement to the switch whereby mechanical operation of the piezoelectricelement applys a voltage to the ignition electrode sufficient to producea breakdown between the I main electrodes of the tube with the supplyvoltage applied to said, supply terminals.

1. A light flashing device in combination with a photocamera comprising,a gas discharge flash lamp having two main electrodes and an externalignition electrode, a mechanically operable piezoelectric element havinga pair of output terminals for supplying an electric ignition voltage tosaid ignition electrode, said photocamera comprising at least two lampholders and a member for mechanically operating the piezoelectricelement and coupled thereto, one lamp holder being adapted to hold a gasdischarge lamp and the other lamp holder being adapted to hold ahigh-voltage combustion lamp, and means electrically connecting theterminals of each lamp holder to the output terminals of thepiezoelectric element so that one output terminal of the piezoelectricelement is connected to the ignition electrode of the discharge lampthrough a substantially impedance-free connection and the other outputterminal of the piezoelectric element is connected to a main electrodeof the lamp through a second substantially impedance-free electricconnection.
 2. A light flashing device in combination with a photocameracomprising, a gas discharge flash lamp having two main electrodes and anexternal ignition electrode, a mechanically operable piezoelectricelement having a pair of output terminals for supplying an electricignition voltage to said ignition electrode, said photocamera comprisinga member for mechanically operating the piezoelectric element andcoupled thereto and a lamp holder adapted to hold both a gas dischargelamp and a high-voltage combustion lamp, means connecting one outputterminal of the piezoelectric element to the ignition electrode of thedischarge lamp through a substantially impedance-free connection thatincludes a terminal of the lamp holder, and means connecting the otheroutput terminal of the piezoelectric element to a main electrode of thelamp through a second substantially impedance-free electric connectionthat includes a second terminal of the lamp holder.
 3. A light flashingdevice in combination with a photocamera comprising, a gas dischargeflash lamp having two main electrodes and an external ignitionelectrode, a mechanically operable piezoelectric element having a pairof output terminals for supplying anelectric ignition voltage to saidignition electrode, said photocamera comprising a member formechanically operating the piezoelectric element and coupled thereto andan adapter for mounting and electrically coupling a gas discharge lampand a high-voltage combustion lamp to the terminals of the piezoelectricelement, said piezoelectric element being mounted in said adapter, meansconnecting one output terminal of the piezoelectric element to theignition electrode of the discharge lamp through a substantiallyimpedance-free connection, and means connecting the other outputterminal of the piezoelectric element to a main electrode of the lampthrough a second substantially impedance-free electric connection.
 4. Alight flashing device comprising, an electric discharge tube having twomain electrodes and an external ignition electrode, a mechanicallyoperable piezoelectric element having a pair of output terminals forsupplying an electric ignition voltage to said ignition electrode, apair of supply terminals connected to the main electrodes of the tubeand adapted to be connected to a source of voltage that is lower thanthe tube ignition voltage, means connecting one output terminal of thepiezoelectric element to the ignition electrode of the discharge tubethrough a substantially impedance-free coNnection, and means connectingthe other output terminal of the piezoelectric element to a mainelectrode of the tube through a second substantially impedance-freeelectric connection, said piezoelectric element including an auxiliarycircuit with which the operating member for the piezoelectric elementcan be operated manually, said auxiliary circuit further comprising aswitch for switching current to the main electrodes of the tube, andmeans mechanically coupling the operating member for the piezoelectricelement to the switch whereby mechanical operation of the piezoelectricelement applys a voltage to the ignition electrode sufficient to producea breakdown between the main electrodes of the tube with the supplyvoltage applied to said supply terminals.